title: Effects of propofol anaesthesia on thoraco-abdominal volume variations during spontaneous breathing and mechanical ventilation.
abstract: BACKGROUND
  Anaesthesia based on inhalational agents has profound effects on chest wall configuration and breathing pattern. The effects of propofol are less well characterised. The aim of the current study was to evaluate the effects of propofol anaesthesia on chest wall motion during spontaneous breathing and positive pressure ventilation.
  
  
  METHODS
  We studied 16 subjects undergoing elective surgery requiring general anaesthesia. Chest wall volumes were continuously monitored by opto-electronic plethysmography during quiet breathing (QB) in the conscious state, induction of anaesthesia, spontaneous breathing during anaesthesia (SB), pressure support ventilation (PSV) and pressure control ventilation (PCV) after muscle paralysis.
  
  
  RESULTS
  The total chest wall volume decreased by 0.41 ± 0.08 l immediately after induction by equal reductions in the rib cage and abdominal volumes. An increase in the rib cage volume was then seen, resulting in total chest wall volumes 0.26 ± 0.09, 0.24 ± 0.10, 0.22 ± 0.10 l lower than baseline, during SB, PSV and PCV, respectively. During QB, rib cage volume displacement corresponded to 34.2 ± 5.3% of the tidal volume. During SB, PSV and PCV, this increased to 42.2 ± 4.9%, 48.2 ± 3.6% and 46.3 ± 3.2%, respectively, with a corresponding decrease in the abdominal contribution. Breathing was initiated by the rib cage muscles during SB.
  
  
  CONCLUSIONS
  Propofol anaesthesia decreases end-expiratory chest wall volume, with a more pronounced effect on the diaphragm than on the rib cage muscles, which initiate breathing after apnoea.
authors.affiliation: TBM Lab, Dipartimento di Bioingegneria, Politecnico di Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Aliverti
authors.forename: P
authors.initials: P
authors.lastname: Kostic
authors.forename: A
authors.initials: A
authors.lastname: Lo Mauro
authors.forename: M
authors.initials: M
authors.lastname: Andersson-Olerud
authors.forename: M
authors.initials: M
authors.lastname: Quaranta
authors.forename: A
authors.initials: A
authors.lastname: Pedotti
authors.forename: G
authors.initials: G
authors.lastname: Hedenstierna
authors.forename: P
authors.initials: P
authors.lastname: Frykholm
mesh_terms: D034841:Abdominal Cavity / Q000502:physiology*; D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010991:Plethysmography; D011175:Positive-Pressure Respiration; D015742:Propofol; D012119:Respiration; D012121:Respiration, Artificial; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics / Q000502:physiology*; D012132:Respiratory Muscles / Q000502:physiology; D012272:Ribs / Q000502:physiology; D035441:Thoracic Wall / Q000187:drug effects / Q000502:physiology; D013909:Thorax / Q000502:physiology*
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol